An on-demand tunable energy absorption system to resolve multi-directional impacts

Energy absorption structures with on-demand tunable mechanical response are urgently needed when dealing with sudden impacts. However, most impact-resistant structures cannot flexibly adjust the mechanical properties to accommodate capricious load characteristics once manufactured. A modular energy absorption system is proposed in this work to combine efficient and tunable properties, which can be easily assembled by bamboo-inspired thin-walled tubes without applying extra constraints. Both high-speed drop hammer impact experiment and finite element simulations have been carried out to investigate the dynamic response of the proposed system and verify its multi-directional self-locking capability. Moreover, based on the interchangeability of the tubes, tunable mechanical response can be achieved through stiffness gradient design and geometrical tailoring. Furthermore, the arranging of tubes for target property shows such strong robustness that the irregularity of arrangement can hardly affect the mechanical behavior of system, allowing for a further improvement on the response speed and property tunability. Compared to existing self-locked systems with same equivalent density, the specific energy absorption and energy absorption efficiency can be respectively enhanced by at least 105% and 225%, which are attributed to the efficient and stable deformation mode of the tubes. This study represents an effective strategy for designing and optimizing high-performance energy absorption devices for multiple applications.